Thomas Aquinas, on Heb 8:12

“Because I will be merciful to their iniquities, and their sins I will remember no more.”

“411. – Then when he says, because I will be merciful to their iniquities, he states the third effect, which is the remission of guilt, which the Old Testament was unable to do: It is impossible that with the blood of oxen and goats sin should be taken away' (Heb. 10:4). He says, therefore: I will be merciful. But iniquity differs from sin, because iniquity is opposed to justice which, strictly speaking, is always toward someone else; therefore, iniquity refers to that by which one person injures another: 'Your wickedness may hurt a man that is like you' (Jb. 35:8). But a sin refers to any defect in an action, because it implies a disorder; hence, iniquity is, properly speaking, against one's neighbor, but sin against oneself. This is, strictly speaking, but in a wide sense both are the same. In regard to this he says, I will be merciful toward their iniquities, namely, in the present life by relaxing the punishment; and their sins I will remember no more, namely, in the future by punishing sins: 'I will not remember all his iniquities which he has done' (Ez. 18:22): 'Forgive us our sins for your name's sake' (Ps. 78:9); 'Remember not our former iniquities' (Ps. 78:8); 'The gifts and the call of God are without repentance' (Rom. 11:29), i.e., God does not repent that He remitted our sins here, as though to punish them again.”

Imported from an open dataset — not yet checked against the printed edition.